textproduct: Rapid City

KEY MESSAGES

- Cold temperatures overnight with freeze/frost headlines

- Gradual warmup mid-week with increasing precipitation chances for Thursday/Friday

- Sharp warmup for the weekend into early next week

UPDATE

Issued at 919 PM MDT Mon May 18 2026

Going forecast in pretty good shape. Clouds are starting to breakup as leftover diurnal showers wane per shortwave moving into the upper Midwest. This will allow temperatures to drop into the upper 20s to lower 30s over much of the CWA overnight, covered by Freeze/Frost headlines.

A warming trend begins tomorrow and peaks over the weekend. Weak disturbance and a bit of buoyancy may pop weak convection Wednesday with better chances Thursday/Friday as stronger disturbances rotate through the northern Rockies into the northern Plains. Ensemble spreads tight, but then diverge a little for the weekend into early next week, but most paint a sharp warmup in line with flat upper ridge/westerly downslope flow.

DISCUSSION

(This Evening Through Monday) Issued at 128 PM MDT Mon May 18 2026

Current Water Vapor and upper air models show troughing just east of the Rockies running through the northern and central plains, with upper ridges over the New England region and off the west coast. 19Z surface analysis depicts a surface low to our east over MN, surface high over central MT. Radar shows widespread precipitation across the forecast area, with some of the higher elevations receiving light accumulations of snow today. Winds are currently breezy out of the northwest to north, with temperatures in the 30s to low 40s.

Precipitation will taper off from west to east late afternoon through the evening, as trough slides eastward today. Cool temperatures continue tonight as clouds clear up and light northwest winds continue. Much of the area is expected to reach near or below freezing overnight. HREF probability for temps to reach at or below freezing sit at 80-100% for areas from the Black Hills and west. Further east will be a bit trickier as cloud cover will linger into tonight as the trough slowly shifts eastward. A Freeze warning has been issued for most of our plains areas, with a frost advisory in effect for part of south-central SD for Tuesday morning.

Brief and weak ridge sets over the region mid-week, resulting in drier conditions and a warming trend towards near seasonable. Another wave rides southeast from western Canada towards the northern plains later in the week, increasing chances for precipitation late Thursday into Friday. Shortwave ridging moves over the weekend, bringing warmer temps back in as well. By Sunday/Monday the region should see highs climb back into the 80s to low 90s.

AVIATION

(For the 18Z TAFS Through 18Z Wednesday) Issued At 1051 AM MDT Tue May 19 2026

VFR conditions expected through the forecast period. Low & mid- level clouds over western South Dakota will gradually dissipate this afternoon from west to east.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.